Anti-sliding performance of parallel wire strand clamps at elevated temperatures

Abstract

This study investigated the influence of temperature on the anti-sliding performance of prestressed parallel wire strand clamps (PWSCs) through experiments and numerical analyses. The ultimate anti-sliding resistance of the clamps at different temperatures was obtained through steady-state experiments, and formulae for calculating high-temperature reduction factors of anti-sliding resistance were proposed. When the temperature reaches 400 °C, the ultimate anti-sliding resistance that the cable clamps can withstand is only 20.8% of the ambient temperature. The function between the ultimate fire resistance time of the PWSC and thrusting load level was proposed under ISO-834 heating conditions through transient-state experiments. It was found that the higher the thrusting load level, the shorter the fire resistance time that the PWSC can withstand. When the load level is 0.9Ffc,20, the fire resistance time of the specimen is only 38.1% of that under 0.3Ffc,20. The bolt pretension loss process of PWSCs under high temperatures was studied through numerical simulations of steady-state experiments. At 400 °C, the pretension of the bolt was only 67.3% of that at 20 °C. On this basis, a refined calculation formula for the high-temperature bolt pretension loss was proposed on the basis of the numerical results. The findings of this research can further improve the fire resistance design of prestressed steel structures.